The invention in its several species is a novel embodiment of a clamp assembly comprising a plural actuating means, three jaws, plural jaw pairs, means to relatively array work holders, separate positioning means for each jaw, one jaw common to plural co-acting jaws, means for lateral adjustment of jaws, screw type means to lock and actuate jaws, with pivoted eccentric cam means to lock and actuate in one model, with a cam acting in a slot or groove, with a cam on end pivoted hand lever, with hand adjustment of right and left threaded screws.